Vacuum centrifuge



June 1967 H. STALLMANN VACUUM CENTRIFUGE 2 Sheets-Sheet 1 Filed June 5, 1965 June 27, 1967, H. STALLMANN 3,327,938

VACUUM CENTRIFUGE Filed June 8, 1965 2 Sheets-Sheet 2 Fig.2

E Z1 Z2 Fig. 3

United States Patent 3,327,938 VACUUM CENTRIFUGE Hans Stallmann, Osterode am Harz, Germany, assignor to Fir-ma Martin Christ, Osterode am Harz, Germany, a

The present invention relates to centrifuges and, more in particular, the invention concerns a vacuum centrifuge for very high numbers of revolutions, in particular, an ultra centrifuge. The rotor of such an ultra centrifuge is arranged to operate in a vacuum chamber in order to reduce atmospheric or air friction.

'In order that the vacuum in the chamber may be maintained it is necessary to seal the passage for the rotor shaft between the shaft and the wall of the chamber. A vacuum centrifuge is known where the shaft which extends through the housing of the vacuum chamber is joumalled in a bearing sleeve which is amply supplied With oil so that the oil between the shaft and the bore acts as a seal. However, the vacuum in the chamber continuously draws oil out of the sealed passage so that a constant loss of oil results.

While care is taken generally that the oil can be replenished from a supply container provided therefor, and that in the event of lack of oil in the container the centrifuge is automatically stopped, there is the awkward disadvantage for the operator that the supply container must be observed continuously and replenished. In addition, a sufficient supply of oil must be held in store, as the oil which leaves the bearing cannot normally be reused due to the impurities it may contain.

In accordance with the invention this problem is solved in that in a centrifuge having a rotor running in a vacuum the leakage oil is automatically returned to the bearing oil container.

Further advantages and details of the invention will become apparent from the following description of an embodiment of a vacuum centrifuge incorporating the invention as illustrated in the drawing, in which FIG. 1 illustrates an embodiment of the invention,

FIG. 2 is a block diagram of a circuit for delaying the operation of the magnetic control valve, and

FIG. 3 shows a switching arrangement for operating the control valve circuit.

The rotor housing 1 is closed with a cover 2 and sealed with a vacuum seal 3. The housing is evacuated by the pump unit 5 by way of conduit 4. The pressure in the housing 1 is reduced to about mm. Hg in order to reach a velocity of 60,000 rpm. A driving means or assembly 8 such as a motor drives the rotor 6 by way of its shaft 7. The bearing sleeve 9 is supplied With oil through conduit 10 from a supply tank 11. This tank 11 is disposed at a somewhat higher level than the bearing sleeve 9, so that the oil may flow to the bearing under gravitational force. An oil passage space in the form of an annular chamber 12 is provided above the bearing sleeve 9 through which the rotor shaft '7 extends. A conduit 13 connects the annular chamber 12 with the sump 14. A conduit of relatively small cross-section leads from the bottom of sump 14 to a container 16 which, in turn, is disposed somewhat higher than the supply tank 11.

The bottom of container 16 is connected with tank 11 by way of a tubular conduit 17 which is provided with a magnetic valve 18. During operation of the centrifuge the magnetic valve 18 is closed so that the conduit 13, sump 14, conduit 15 and container 16 are below 3,327,938 Patented June 27, 1967 normal pressure or in a vacuum. The leakage oil leaving the annular chamber 12 flows into the sump 14 by way of conduit 13 and partly also into the conduit 15.

When the vacuum pump 5 is shut off at the end of a centrifuging operation and the housing 1 is supplied with air through the valve 19, the incoming air forces the oil collected in the sump through the conduit 15 into container 16', which is still in an evacuated condition as a result of the preceding centrifuging operation. The sump 14 is emptied of oil which flows into the container 16 and is thus prepared for receiving further leakage oil during the next operation. The valve 18 provided in the conduit 17 opens after a short time delay and permits the oil accumulated in the container 16 to flow into the supply tank 11. The delayed opening of the valve 18 can be achieved in a known manner by a delaying element connected after the valve 19 or by a different necessary operation of the apparatus, for example, in response to the opening of the cover 2 of the apparatus. Evidently a centrifuge constructed in accordance with the invention no longer requires the cumbersome operation of manually replenishing the oil.

FIG. 2 is a block circuit diagram of a circuit by means of which the operation of the magnetic valve 18 is delayed after valve 19 has opened. The valve 19 or its electromagnet is actuated by way of a switch 20. As the valve 19 is actuated a delaying circuit, for example, a time delay relay or the like, is operated which after expiration of a predetermined time period actuates the opening switch 22 for the valve 18 or its electromagnet.

FIG. 3 illustrates the manner in which a switch 1s provided at the wall of the rotor housing 1 and on the cover 2. As shown the cover 2 extends outwardly over the upper border of the Wall of the rotor housing. A support 23 is provided on the wall of the chamber upon which a switch S is mounted, as indicated in dotted lines. This switch includes two stationary contacts 26 and 27 which are engaged by a yoke 24 when the cover 2 s raised permitting the operating member 25 which is schematically illustrated to raise the yoke 24 under the pressure of a spring (not illustrated). A battery B 1s connected in series with the contacts 26 and 27 and with the circuit element 22. This element actuates the electromagnet of the valve 18. Furthermore, in series wlth the battery and the two contacts 26 and 27 a single blade switch 28 is connected which is closed as the centrifuge is operative, as indicated in dotted lines, and which 1s opened when the centrifuge is not in operation, so that when the cover 2 is removed, the battery may be disconnected from the circuit.

The oil return system in accordance with the invention can be incorporated in an analogous manner 1n centrifuges where the rotor is suspended, i.e., In an arrangement in which the drive assembly such as a motor is disposed above the housing. In that event a centr fuging disk would be mounted on the shaft of the centrifuge which feeds the leakage oil into an annular chamber analogous to chamber 12 and thence to a container that corresponds to container 14 of the illustrated embodiment.

Having now described my invention with reference to the embodiment illustrated in the drawing, I do not wish to be limited thereto, but what I desire to protect by Letters Patent of the United States is set forth in the appended claims.

I claim:

1. A centrifuge comprising a housing including closure means therefor, driving means disposed externally of said housing, a rotor disposed in said housing and having a shaft extending to said driving means, a bearing Sleeve disposed around said shaft intermediate said rotor and said driving means, evacuating means such as a pump connected to said housing for creating a vacuum, an oil supply tank connected to supply lubricant to said bearing sleeve and said shaft, and means associated with said bearing sleeve operative to collect leakage oil and to return the oil automatically to said supply tank, said means including an oil passage space around said shaft, a sump disposed externally of said housing, a conduit connecting said passage space to said sump, a container for oil disposed at a level above said supply tank and a conduit connecting said sump to said container, a tubular conduit connecting said container with said supply tank, and a magnetic valve connected in said tubular conduit operative to control the flow of oil from said container to said supply tank.

2. A centrifuge comprising a housing including closure means therefor, driving means disposed externally of said housing, a rotor disposed in said housing and having a shaft extending to said driving means, a bearing sleeve disposed around said shaft intermediate said rotor and said driving means, evacuating means such as a pump connected to said housing for creating a vacuum, an oil supply tank connected to supply lubricant to said bearing sleeve and said shaft, and means associated With said bearing sleeve operative to collect leakage oil and to return the oil automatically to said supply tank, said means including an oil passage space around said shaft, a sump disposed externally of said housing, a conduit connecting said passage space to said sump, a container for oil disposed at a level above said supply tank and a conduit connecting said sump to said container, a tubular conduit connecting said container with said supply tank, a magnetic valve connected in said tubular conduit operative to control the flow of oil from said container to said supply tank, and valve means associated with said pump and connected to said housing operative to admit air to said housing upon disc0ntinuance of the operation of said pump and means adapted to delay the operation of said magnetic valve until after operation of said valve means.

3. A centrifuge comprising a housing including closure means therefor, driving means disposed externally of said housing, a rotor disposed in said housing and having a shaft extending to said driving means, a bearing sleeve disposed around said shaft intermediate said rotor and said driving means, evacuating means such as a pump connected to said housing for creating a vacuum, an oil supply tank connected to supply lubricant to said bearing sleeve and said shaft, and means associated with said bearing sleeve operative to collect leakage oil and to return the oil automatically to said supply tank, said means including an oil passage space around said shaft, a sump disposed externally of said housing, a conduit connecting said passage space to said sump, a container for oil disposed at a level above said supply tank and a conduit connecting said sump to said container, a tubular conduit connecting said container with said supply tank, a magnetic valve connected in said tubular conduit operative to control the flow of oil from said container to said supply tank, and means including a switch associated with the cover of said housing and connected to said magnetic valve operative to open said magnetic valve upon removal of said cover.

References Cited UNITED STATES PATENTS M. CARY NELSON, Primary Examiner. 

1. A CENTRIFUGE COMPRISING A HOUSING INCLUDING CLOSURE MEANS THEREFOR, DRIVING MEANS DISPOSED EXTERNALLY OF SAID HOUSING, A ROTOR DISPOSED IN SAID HOUSING AND HAVING A SHAFT EXTENDING TO SAID DRIVING MEANS, A BEARING SLEEVE DISPOSED AROUND SAID SHAFT INTERMEDIATE SAID ROTOR AND SAID DRIVING MEANS, EVACUATING MEANS SUCH AS A PUMP CONNECTED TO SAID HOUSING FOR CREATING A VACUUM, AN OIL SUPPLY TANK CONNECTED TO SUPPLY LUBRICANT TO SAID BEARING SLEEVE AND SAID SHAFT, AND MEANS ASSOCIATED WITH SAID BEARING SLEEVE OPERATIVE TO COLLECT LEAKAGE OIL AND TO RETURN THE OIL AUTOMATICALLY TO SAID SUPPLY TANK, SAID MEANS INCLUDING AN OIL PASSAGE SPACE AROUND SAID SHAFT, A SUMP DISPOSED EXTERNALLY OF SAID HOUSING, A CONDUIT CONNECTING SAID PASSAGE SPACE TO SAID SUMP, 